The field of the invention relates to treating and gravel packing oil and gas and other types of wells. Some producing wells contain producing zones that have loose sand. Flow of the desired liquid or gas from such zones into the well bore often carries undesirable amounts of sand which can cause erosion of the equipment and can cause plugging of the flow passages. It has been found that provision of a screen pipe within the perforated producig zone with suitable small size holes or slots provided in the screen pipe and having the annulus between the screen pipe and the casing filled with a suitable size gravel of a predetermined screen size allows passage of the desired fluids from the producing zone and prevents passage of the same. Producing zones also sometimes require treatment in order to increase the area of flow passages to the well bore to permit greater drainage of the producing zone into the well bore. It is sometimes desired to treat a producing zone with acid or another fluid to increase the productivity of the zone.
The prior art includes crossover arrangements whereby gravel can be pumped into an annulus between a screen pipe and the casing by providing a crossover flow arrangement communicating a tubing string to an annulus below a packer outside a screen pipe and providing a return passage through the packer communicating with the annulus outside the tubing above the packer. The prior art in treating producing zones with acid or other fluids includes a simple or heavy duty packer connected to a tubing string allowing the treating fluid to be pumped to an area adjacent the producing zone, allowing displaced fluid to return around an unset packer or through an open valve in the tubing string providing communication between the tubing and the casing above the packer. However, it has heretofore been unknown in the art to provide a single apparatus selectively capable of performing both functions.
It is therefore an object of this invention to provide an apparatus for selectively treating and gravel packing a well.
It is a further object of this invention to provide apparatus and method for gravel packing and treating a well without removing the tubing between the treating and gravel packing operations.
It is a still furher object of this invention to provide apparatus and method for acidizing and gravel packing a producing zone in a well.
It is a still further object of this invention to provide completely retrievable apparatus for treating and gravel packing a producing zone in a well.
It is a still further object of this invention to provide a selectively operable apparatus for treating and gravel packing a well without imposing the pressure required for treating the zone on the casing above the packer.